Science and Technology Crossword 9

Click on a number in the crossword, write your answer, and then click "Enter". (Click "Hint" if you need help to get the next letter in each word.)
1    2       3   
        
4      5      
        
6          
        
7       8     
    9      

Across

1. One of the planets
4. Height above sea level
6. Convert into an ion
7. Numerical series midpoint
9. Geological time periods

Down

1. Nuclear reactor fuel
2. Maximum displacement in a standing wave system
3. Performs a surgical procedure
5. Seed coats
8. Symbol of "nobelium"